1. Field of the Invention
This invention relates to railroad cars and locomotives and more particularly to a liner adapted to be positioned between the center plate bowl of the truck bolster and the center plate of the body bolster to reduce friction and prevent wear.
2. Description of the Prior Art
It has been recognized that wear between the center plate and the center plate bowl can be reduced by inserting a wear plate or liner between them. In addition to reducing wear, the insert, if made from a nongauling, low friction material, will prevent seizures and enable the truck to rotate relative to the car body more readily.
Various plastic materials have been used as a bearing surface between the center plate and the bowl, including thermosetting materials such as reinforced phenolics, and thermoplastic materials such as nylon; polyesters; low temperature polymerizing, nonelastic polyurethanes; and polyolefins.
The use of ultra-high molecular weight polyethylene to make wear elements in a center plate bowl of a railroad truck is well known and is disclosed, for example, in U.S. Pat. Nos. 3,944,298 and 4,075,951. Also, of background interest, is U.S. Pat. No. 3,405,654 which discloses a center plate liner made from an elastomeric polyurethane.
None of the devices of the prior patent art have the capability of insuring an intimate seal both between the liner and the inside wall of the center plate bowl and between the liner and the outside wall of the center plate. A seal on both sides of the liner is desirable since it will prevent debris from working its way into the center plate assembly that could cause abrasion or other damage to the bearing surfaces.
The device disclosed in U.S. Pat. No. 3,405,654 obtains an effective seal between the rim of the bowl and the bowl liner but not between the liner and the center plate. Further, to achieve a seal in accordance with this patent, the liner must be made from elastomeric materials which generally have high coefficients of friction and do not wear well in bearing applications.
A center plate liner such as shown in U.S. Pat. No. 4,075,951 obtains a seal between the liner and the neck portion of the center plate but does not provide a seal between the liner and the bowl. Further the liner of this patent relies on a freestanding flange which is exposed to damage when the center plate is dropped into position within the bowl.
Accordingly it is an object of this invention to provide a wear resistant center plate liner that will provide an effective seal between the liner and the bowl on the one hand and between the liner and and the center plate on the other hand.
Another object of this invention is to provide a center plate liner that will not be damaged when the center plate is dropped into position but instead will guide the center plate to seat within the center plate bowl.
These and other objects of this invention are achieved by providing a center plate liner in the form of a bowl adapted to be positioned between the facing surfaces, including the floor and sidewalls, of the center plate and the center plate bowl in which the sidewall of the liner carries an upwardly and outwardly directed flange adapted to rest initially upon the rim of the bowl. The liner is made slightly shallower than the bowl so that when the liner is loosely positioned within the bowl with the flanges of the liner resting on the rim of the bowl, the bottom of the liner is held a small distance above the bottom of the bowl. However, when the center plate is dropped into position and the weight of the car bears against the liner, the liner will be seated in the bottom of the bowl causing the flange on the sidewall of the liner to be deformed or extruded into intimate contact with both the sidewalls of the bowl and the center plate.